Certain sex-dependent differences in drug and steroid metabolism by hepatic enzyme systems in adult rats are imprinted neonatally by testicular androgen(s). Much attention in this and other laboratories has focused on defining the mechanism of androgen imprint at the level of the hypothalamic-pituitary axis. The present proposal emphasizes the effects of imprinting at the level of both the hepatic microsomal monooxygenase system and the hepatic cytosol glutathione S-transferase B system. In the study of hepatic microsomal monooxygenase system, the main objectives are: (1) To refine techniques in order to provide definitive documentation of the existence of a sex-dependent form(s) of cytochrome P450 in untreated adult male rats. Priority will be given to the improvement of techniques used in the reconstitution of catalytic activity and to the characterization of an antibody raised against this hemoprotein. (2) To correlate the biochemical characteristics of the imprinted animal, and the molecular properties of the sex-dependent form(s) of cytochrome P450. Such imprinted characteristics include the apparent Km of ethylmorphine N-demethylase, responsiveness of this enzyme activity to testosterone, the 16 alpha-hydroxylase of testosterone, as well as other imprinted steroid hydroxylases, and the turnover of cytochrome P450. (3) To elucidate the directive role of neonatal androgen on the development of the sex-dependent form(s) of hepatic cytochrome P450. The dependency of imprinting on the genetic sex of the animal, and on the age or the differentiative states of the liver cells will be examined. In the study of hepatic soluble glutathione S-transferase B system, we intend to purify this enzyme to homogeneity. We will prepare anti-glutathione S-transferase B antibody. This antibody will serve as probe to investigate the mechanisms of neonatal androgen imprinting on the glutathione S-transferase B.